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Reduced gain in HMC998APM5E controlled by HMC980

Category: Hardware

Hi there,

I'm using the HMC998 with HMC980 in my circuit that follows roughly the same circuit as their evaluation boards. I'm running the amp from 15V VDD and setting the R sense to 300R for the 500mA operation of the amp. However, when measuring the gain, I'm not getting the full gain/P1dbm out of the amp, what could be wrong? 

Although I have set the resistor divider in the controller for 9V5, I'm reading 8V5 at the gate voltage of the amp. I've attached my amp circuit diagram below (for operation at 12 GHz). Any suggestions would be appreciated!